Apparatus for congealing liquids

ABSTRACT

Congealing apparatus is disclosed which is particularly suited for freezing ice and congealing liquid products. There are two refrigerated plates over which a steel belt passes in two runs at an angle to the horizontal. A heat conducting lubricant is supplied beneath the belt as it starts along each run. A special arrangement is provided for removing ;the lubricant at the bottom of the path of the belt and special means is provided to evaporate water from the lubricant.

United States Patent [72] Inventor Crosby Field 3,004,396 10/1961 Endress et a1 62/472 X 8029 Hnbor View Terrace, Brooklyn, N.Y. 3,258,486 6/1966 202/ 1 58 X 11209 3,491,543 l/l970 62/85 X 211 Appl. No. 8,118 3,301,773 l/1967 203/2 x [22] Filed Jan. 21, 1970 3,332,856 7/1967 203/2 X [23] Division of Ser. No. 691,055, Dec. 15, 1967, 2,057,938 10/1936 62/171 Patent No. 3,491,543 3,358,739 12/1967 Pinkerton et a1. 159/8 [45] Patented Sept 1971 Primary Examiner-Norman Yudkofi Assistant Examiner-J. Sofer s41 APPARATUS FOR CONGEALING LIQUIDS Mowkcums,

4 Claims, 18 Drawing Figs.

[52] US. Cl. 159/1, 159/22, 159/94, 62/472 I511 2 s ABSTRACT: Congealing apparatus is disclosed which is par- Bold 1/00 F2511 3/02 ticularly suited for freezing ice and congealing liquid products. [50] Field of Search 159/ 1 30, There are two f i t d plates over which a steel belt passes 44,13 12; 62/472; 202/158; 203/2 in two runs at an angle to the horizontal. A heat conducting lubricant is supplied beneath the belt as it starts along each [56] Rehnnces Cited run. A special arrangement is provided for removing ;the UNITED STATES PATENTS lubricant at the bottom of the path of the belt and special 2,816,858 12/ 1957 Walker 202/ 1 58 X means is provided to evaporate water from the lubricant.

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PMWED; SEP28 3.608 608 SHEET 1 OF 4 INVENTOR. C ROSBY FIE L0 PATENTEBSEPQBHH CROSB FlELD PATENTED was IHYI sum 3 [1F 4 FIG .6

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FIG.

INVENTOR- C ROSBY F IE L D APPARATUS FOR CONGEALING LIQUIDS in my U.S. Pat. Nos. 2,610,479, 2,610,476 issued Sept. l6,

1952, 2,990,199 issued June 27, 1961, and 3,037,366 issued June 5, 1962.

An object of this invention is to provide improved freezing apparatus. Another object is to provide evaporators having a high rate of heat transfer and also with a surface hardened against erosion and protected against corrosion. Another object is to provide a very sensitive method of maintaining close and uniform contact between a stationary evaporator and a freezing belt travelling over it. Another object is to provide a method of tracking such belts. Still another object is to double the output of such a freezing belt by having it pass over the surface of an additional evaporator on the return from the idler pulley to the drive pulley, after passing over the surface of the evaporator between the drive pulley and the idler pulley, as disclosed in my previously cited patents. Another object of the invention is to provide a separator, such as an air dam, between the unfrozen liquid and the ice so as to produce dry and subcooled ice on the belt. These and other objects will be in part obvious and in part pointed out below.

In the drawings which show one embodiment of the invention;

FIG. 1 is a right-hand side view, with refrigeration side of the cabinet removed;

FIG. 2 is a diagrammatic view of the refrigeration system;

FIG. 3 is a rear view of the rear side of the cabinet removed;

FIG. 4 is a diagrammatic view of the system for tracking the belts;

FIG. 5 is a diagrammatic view of the belt lubricating system;

FIG. 6 is a representation of the groove pattern in the evaporators for distributing the lubricant;

FIG. 7 is a diagrammatic view of the drive system;

FIG. 8 is a cross section of one evaporator on the line 8-8 of FIG. 1;

FIG. 9 is an enlarged fragmentary view of a portion of FIG.

FIG. 10 is a diagrammatic view of the precooling system;

FIG. 11 is a transverse sectional view of the belt;

FIGS. 12 and 13 are fragmentary side views of the portions of one evaporator;

FIG. 14 is a somewhat diagrammatic view showing the manner in which the lubricant is collected; and,

FIGS. 15 to 18 are enlarged sectional views, respectively on lines 15-15 and l6 -l6 of FIG. 12, 17-17 on FIG. 14, and 18-18 on FIG. 17.

Referring particularly to FIGS. 1 and 3 of the drawings, the ice maker has four evaporators l assembled with evaporator frames 3 in the manner more fully described hereinafter. The four subassemblies of evaporators l and evaporator frames 3 are supported by a base frame 5 bolted to it means of brackets 7. Wooden skids 13 form an insulating foundation for the metal base frame 5. This frame has two central support members 6 and 8 which carry two centrally supported tubular arms 10 which, in turn, support slant portions of the frame 5 cantilevered on both sides. These two identical slant portions carry ice making subassemblies which are also identical except that they are left-hand and right-hand respectively. The following description of the right-hand subassembly (near side in FIG. 1) applies equally to the one on the left. The evaporator subassemblies are mounted in upper and lower slant positions as shown. Pads of rubber 9 provide cushioned mountings on the brackets 7 that permit final adjustment of the alignment of the evaporators 1 by means of bolts 11, which by means of their nut 12 control the compression of the pads 9.

As best shown in FIG. 1, a weldment 21 is bolted to the upper end of frame 5 and supports four parallel guide rods 23, two on each side. The guide structure is completed by end plates 25 secured to the ends of guide rods 23 by screws 27. Bearing block 31 is bored to slide on guide rods 23, thus permitting the bearings to move longitudinally of the slant frame. Each of the pair of bearing blocks 31 has a bearing 33 for an idler shaft 35. Mounted upon a free turning shaft is an idler pulley 37. A drive pulley 19 is keyed to a shaft 17, which is rotatably mounted in the pair of bearings 15 secured to the lower ends of the slant members of frame 5. Freezing belt 39 is supported by pulleys 19 and 37 and is tensioned between them as will be described more fully hereinafter. Movement of belt 39 is imparted to it by drive pulley l9. Pulleys 19 and 37 are of rigid metal and have their cylindrical faces covered by a layer 41 of an elastomer, such as rubber (see FIG. 14). Pulley 29 is driven as described hereinafter in connection with FIG. 7. The frame 5 is built so that the line between the centers of the shafts of the pulleys 19 and 37 may make with any horizontal line any angle between 45 above to 45 below horizontal. As pulley 19 turns, it drives the belt 39 so that it is drawn along the curved top surface of the upper evaporator and along the curved bottom surface of the lower evaporator. The portions of the belt in contact with the evaporators are maintained at a low temperature. As shown in FIG. 4, the belt is held under tension by rods which bear upward against bearing blocks 31. The force on the inner rod 43 is produced by a coaxial spring 45 which is screw adjusted for changing the pressure. The force on the outer rod 43 is produced by a coaxial spring 45 which is screw adjusted for changing the pressure. The force on the outer rod 43 is produced by a coaxial hydraulic cylinder 47 which is automatically controlled as described hereinafter. The belt is driven by pulley 19 in a clockwise direction in FIG. 1; that is, with the upper run moving to the right.

As shown in FIG. 3 and FIG. 11, each edge of belt 39 has bonded to it a continuous molded darn structure 49 of an elastomer, e.g., rubber. As shown in the cross-sectional view of FIG. 1 1, this dam structure has portions on both sides of the belt; the one portion to retain the liquid or fluid 40 (product) being congealed upon the congealing surface and the other portion to retain the liquid heat transfer lubricant 42 which acts both as a lubricant and as a heat transfer agent between the metal of the belt and the evaporators. By maintaining a thin film of heat transfer lubricant on the undersurface of the belt, any irregularities in the surface in normal contact are compensated for.

The dams 49 are formed with a thinner section on the product side than on the lubricant side. This prevents the edges where the dams 49 meet the metal belt 39 at points 44 from getting cold enough for the product 40 to freeze along its edges.

From drive pulley I9, shaft 17 is extended inwardly beyond bearing 15 (see FIGS. 1 and 7) where sprocket 51 is keyed to it. Sprocket 51 is driven from upper jackshaft 53 by chain 55 and sprocket 56 which is keyed to jackshaft 53. J ackshaft 53 is turned by sprocket 57, driven by chain 63 from motor 291, gear motor sprocket 59 and gear motor shaft 61. Jackshaft 53 turns in two bearings 65, bolted one on either side to the center post of frame 5. A lower jackshaft 67 turns in two bearings 69 which are similarly bolted to the center post of frame 5. Jackshaft 67 is turned by sprocket 71 from chain 63. A hydraulic pump sprocket 73 is driven from this jackshaft by a chain 79 and a sprocket 75, and 73 and chain 79. The sprocket 81 of the lubricant pump is also driven by chain 63. Vertical adjustment of sprocket 81 produces the proper tension in the chain 63. Proper tension in chain 55 is maintained by vertical adjustment of bracket 87 which supports an idler sprocket 83 and its pivot 85.

The evaporator (see FIG. 8) in contact with the freezing belt is a plate of a high heat conducting material, i.e., aluminum, to one side of which has been attached, by brazing or welding, parallel refrigerant tubes 97. The other side of the plate 95 is coated with a hard erosion resistant yet high heat transfer material, i.e., molybdenum, into the pores of which has been inserted a corrosion resistant coat, i.e., a polyvinylchloride, rendered high heat conducting by the inclusion therein of graphite. At the respective ends, tubes 97 are welded into headers 99 and 99a (see also FIG. 1), the flanges 101 (FIG. 8) of which are connected to the refrigerant piping described hereinbelow. In this embodiment, there are refrigerant tubes 97, and the tubes are slightly flattened to increase the contact with the plate, thus increasing the heat transfer rate between the plate 95 and the refrigerant in the tubes. Additional heat transfer is provided by enclosing the tubes in a layer of heat conducting cement 103 which is also in contact with the plate 95.

As shown in FIG. 6, lubricant grooves are provided on the other side of the plate 95. Evaporator plate 95 is supported (FIG. 8) by three radius guide plates 105, of an insulating material, which in turn are supported on their lower edges by the three transverse angles 107 which, together with two longitudinal angles 109 form the evaporator frame 3. Radius guide plates 105 are maintained in the correct transverse positions by rods 111 and spacer nuts 113 which also secure the outer guide plates to the longitudinal angles 109 of the frame. The subassembly includes two insulating strips 115 which extend along the curved sides of the respective outer radius guide plates 105 and up alongside the edge of the evaporator plate. Near the lower edge of strip 115 an insulated heater wire 117 is secured. It is covered by a metal foil strip 119 and then by a plastic insulating strip 121. The heat produced by the electric current in wire 117 is thus conducted by the foil 119 up to the edge of the evaporator isolated by insulators on both sides. The heat along this line prevents frost accumulation under the edge of the metal freezing belt 39.

The upper and lower evaporator assemblies are identical except only in the handling of the heat transfer lubricant. FIG. 12 illustrates the lubricant feed end of the upper evaporator and FIG. 13 illustrates the other end, and FIG. 6 shows the top of the evaporator. The direction of belt travel is indicated by arrows 123. Referring to FIG. 12, casting 125 and insulating block 127 provide end support for plate 95 allowing clearance for header 99 and (see also FIG. 6) lubricant feed block 129, being firmly bolted to the frame at transverse angle 107. The method of securing plates 95 to end castings 125 is shown in FIG. which is a cross section near the end of the evaporator. Screws 120 in countersunk holes in insulating block 127 secure the evaporator to end casting 125, screws 122 in countersunk holes in plate 95 secure it to block 127. Thus there is no metallic contact for heat conductivity between plate 95 and end casting 125. Insulating block 127 prevents frosting on casting 125 by conductivity from plate 95.

As shown in FIG. 16, lubricant is fed into feed block 129 by a nipple 131 and thence by means of holes 124 in screws 126 through the plate 95 to the belt as more fully described hereinbelow. Any excess lubricant not carried up by the belt is collected in drain groove 133 (FIG. 12). Referring to FIG. 13, casting 125a and insulating block 127a provide support for the other end of plate 95. A transverse windshield wiper 135 wipes the bottom surface of the belt as it moves away from the evaporator surface, and removes the film of lubricant and it collects in drain 137. Referring to FIG. 8, a metal sleeve 139, larger in diameter than header 99 covers this header concentrically between the adjacent radius guide plate 105 and the flange 101. I-Ieater wire 117 makes approximately three turns around sleeve 139. Heat conducting cement is used to increase the effectiveness of wire 117 in heating sleeve 139.

After all these evaporator parts have been assembled, the space below the plate 95 and tubes 97 is filled with a chemically expanded insulation (such as a polyurethane foam) flush with the bottom of radius guide plates 105. This insulation also fills the space between headers 99, 992 and sleeves 139 after insulating between the headers and the end castings 125 and 125a. The construction of the lower evaporator assembly is the same as that of the upper evaporator assembly, except that end has a lubricant feed block 129 and connection nipple 131. There are no lubricant drain connections in casting b or insulating block 1271: and no wiper 135, since the lubricant drains into the inside of the lower part of the belt. Its return to the system will be described hereinbelow in connection with FIG. 5. Both upper and lower evaporator plates 95 have lubricant grooves 141 as shown in FIG. 6.

REFRIGERATION OF EVAPORATOR FIG. 2 is a diagrammatic representation of the refrigeration system for the evaporators 1 which omits accessories such as controls, oil separator and others well known in the art. On the low-pressure side two levels of operation are used since the evaporators are operated flooded. The upper evaporator 1a operates in parallel off surge drum 145a and the lower evaporators 1b operate in parallel off surge drum 145k. Liquid refrigerant from condenser 147 is fed through conduit 149 into the surge drums through their respective valves 151a and 151k which are controlled by level responsive elements 153a and 1531) so that the levels in the surge drums are maintained at their respective levels 155a and I55b which are the respective optimum operating levels. The refrigerant liquid flows by gravity from the surge drums into the evaporators. The surge drums are constructed as disclosed in my U.S. Pat. No. 3,037,366. The refrigerant vapor formed in the upper evaporator flows through conduits 157a into surge drum 145a, displaced by liquid refrigerant under the static head at level 155a. The liquid refrigerant flows through an orifice in a nozzle into each of the evaporator tubes 97 to provide proper distribution of refrigerant between the tubes and increase velocity and turbulence therein resulting in a higher rate of heat transfer as disclosed in my U.S. Pat. No. 3,037,366. The refrigerant vapor returns to the compressor 171 via the surge drum 145a where any liquid carried with it is separated out before it enters suction line 163. Oil return is obtained by bleedofi' tubesa and 167a from the lower evaporator headers through the oil stills 169a and 16% and back into the suction line 163 to compressor 171. Oil still 169a is heated by a small amount of discharge gas from compressor discharge line 173 through tubes I75 and 1770 to the top of surge drum 1450. The lower evaporators lb and surge drum 145b operate together, in the same way as the upper evaporators 1a and surge drum 145a, but the operation is based on the lower liquid level 155b.

LUBRICANT SYSTEM FIG. 5 is a diagrammatic representation of the system which maintains a thin film of heat transfer lubricant between the evaporators and the belts. This lubricant may be an antifreeze compound such as an aqueous solution of propylene glycol. The two evaporators and their respective associated elements on the right-hand side of this embodiment have been omitted for clarity. A supply of lubricant is maintained in reservoir 179. When the belts are driven, pump 181 supplies lubricant to the leading ends of evaporators, through filter 182, 1a and 117 via capillaries 183 and 183b and feed blocks 120 (see also FIG. 12). Each of the capillaries 183 may be of a different length to ensure equal and proper distribution of lubricant between the four evaporators. Pump 181 is driven by sprocket 81 as previously described with reference to FIG. 7. Used lubricant from wiper 135 (FIG. 13) and drain 137 returns to reservoir 179 via drain line 185. Drain line 187 returns the lubricant from drain groove 133 (FIG. 12) to reservoir I79. Referring to FIG. 5, the lubricant used by the lower evaporator 1b collects on the inside of the belt 39 at its low point where drive pulley 19 is located.

The molded dam structure 49 at each edge of the belt retains this lubricant (see FIGS. 17 and 18) so that it flows in along the edges of the inside of the pulley. Each of these edges has a large number of equally spaced grooves 188 which lead to four aligned arcuate grooves 189 adjacent the web 190 of the pulley (see FIG. 14). Grooves 188 are spiral so that the rotation of the pulley causes them to direct the lubricant from the extreme edge of the pulley into grooves 189. Positioned at the trailing end of each groove 189 is a cup 191 which is open on their leading sides to its groove. Hence, as the pulley moves clockwise from the bottom position in FIG. 14, the lubricant flows from the groove 189 into its cup. The cup is otherwise closed except for a discharge tube 192 which at this time extends upwardly, but which has its discharge end extending out beyond the edge of the belt toward a stationary drain tray 193. Upon continued movement of the pulley the cup is tipped toward its upright position and the lubricant starts to discharge through tube 192 into the drain tray which is positioned at the side of the pulley adjacent the pulley shaft. Hence, as each cup moves past the lowest point in its travel, it scoops up a quantity of lubricant and then deposits it into tray 193 from which it returns through a tube 195 to reservoir. 179. The arrangement is such that the lubricant is completely discharged from each cup before its tube moves over the pulley shaft and no lubricant is deposited on the shaft. When the ice maker is stopped a timer keeps the belts 39 running for a preset period with the refrigeration off. During this period solenoid valve 197 opens diverting all lubricant from the discharge of pump 181 to reservoir 179 while the abovedescribed lubricant system returns the lubricant in use to reservoir 179 also to prevent loss of lubricant by overflow on shutdown.

Since the lubricant used in water soluble, it may be gradually diluted by moisture condensed from the air as the ice maker operates. Further, since the freezing point is raised by dilution, this accumulation of water must be constantly removed to avoid possible freezeup. Since the boiling point of the lubricant and water mixture is a function of its water content a rectifier 199 is used, maintained at a practically constant temperature by means of an electric immersion heater and thermal switch. The temperature of the rectifier is set to correspond to the boiling point of the desired concentration of lubricant solution. A small convection flow in tubes 201 maintains the solution concentration in reservoir 179 substantially the same as that in rectifier 199 without heating the solution in the reservoir. Thus when the solution is diluted in the reservoir 179, it is also diluted in rectifier 199 depressing its boiling point below the rectifier temperature. The boiling in the reservoir drives water out of the solution, thus concentrating it until its boiling point reaches the predetermined rectifier temperature, at which time the boiling stops. A reflux condenser 203 having glass ball packing is used over the rectifier to minimize loss of lubricant carried off by the escaping steam.

HYDRAULIC TRACKING SYSTEM FIG. 4 is a diagrammatic representation of the hydraulic tracking system which automatically keeps belt 39 centered on evaporators 1a and lb and drive pulley 19 and idler pulley 37 as it runs. A reservoir 205 holds a supply of hydraulic fluid. Pump 207 (driven by sprocket 73 in FIG. 7) draws fluid from reservoir 205 to build up pressure in pressure line 209, limited by a pressure regulator 211 which bleeds into a drain line 213 to return spent fluid to reservoir 205. Each of the two belts in this embodiment is tracked by using this pressure in the following manner: a control valve 215 is operated by a roller arm 217 which follows the molded edge 49 of belt 39. When belt 39 starts to the left of center it causes arm 217 to turn control valve 215 so as to permit more fluid into cylinder 47 increasing the tension slightly in the left side of the belt 39 which moves the belt back to the center position. When belt 39 starts to the right of center it causes am 217 to turn control valve 215 so as to vent fluid from cylinder 47 decreasing the tension slightly in the left side of the belt 39 which moves the belt back to the center position. Spring 45 maintains a practically constant preset tension on'the right side of the belt. The changes in tension on the left side of the belt required for tracking are referenced to this tension and are so slight that they have no noticeable effect on the belt. A check valve 221 is provided between the control valve 215 and the cylinder 47. This valve remains open as long as there is pressure in line 209. When the pump stops and its pressure falls, check valve 221 closes to hold cylinder 47 in the proper position for restarting without excessive tracking movement.

THE WATER SYSTEM Identical systems apply the water (or other liquid or fluid) to be solidified to the refrigerated portions of each of the two belts 39. One of these, therefore, will be described with reference to FIGS. 1 and 3. The liquid enters through tube 223 controlled by float valve 225 which maintains a level 227 in sump 229. It is circulated by pump 231 from the sump through tube 233 to toe 235. To supply the upper freezing portion of the belt, the liquid rises from tee 235 through tube 237 to the high end of upper precooler trough 239, down this trough and then down a second precooler through 241 on to the belt 39. It is distributed across the belt by a corrugated weir 243 at the end of trough 241. Cooling coils 244 and 246 are brazed to the underside of troughs 239 and 241, respectively. The excess liquid that is not frozen as it flows downward and to the left, over the upper refrigerated portion of belt 39 returns to the sump after flowing over drive pulley 19. It is prevented from entering ice chute 245 by an air curtain from a row of nozzles 247 in a header 249. To supply the lower portion of the belt the liquid passes through tube 251 to four sprinkler nozzles 253 connected to tube 251 by tees 255. Noules 253 are so located that the produce complete coverage of the lower freezing portion of belt 39. The nozzles 253 and tube 251 are secured into a rundown pan 257 which has sides curved to fit the belt. Rubber edges 259 on these sides form a splash seal against the rubber edges of belt 39. Another rubber strip 261 across the belt at the top of the upper end of rundown pan 257 forms a splash seal at this point. An air curtain from a row of nozzles 263 in header 265 prevents any unfrozen liquid from following down the belt into ice chute 245. Hence it is all deflected into rundown pan 257 and returns to sump 229 at point 267. A finned cooling coil 269 is submerged in the liquid in sump 229 for precooling the returned unfrozen liquid and the makeup from the float valve 225. A blower 271, direct driven by motor 273 provides the air for the air curtains. Its discharge is divided into four tubes 275. The two shown supply headers 247 and 265. The two behind them supply the air curtains for the other belt. A splash pan 262 fits snugly on top of sump 229. It has an ice chute 245 built into it ans also has a support trough for air header 249 and rundown trough for the excess unfrozen liquid from the upper freezing surface. A lower extension 245A of the ice chute is built into sump 229 to guide the ice harvested from the lower cooling surface through the bottom of the ice maker out of contact with the unfrozen liquid.

PRECOOLER REFRIGERATION As has been indicated above, the liquid to be frozen is precooled by cooling coils on upper troughs 239 and 241 and finned lower coils 269 immersed in the lower sump 229. These coils are cooled by the evaporation of a refrigerant in a system in conformity with general practice diagrammed in FIG. 10. The liquid refrigerant flows from the receiver 277 under control of solenoid valve 279. Its flow is properly distributed between the four evaporators by means of four adjustable needle valves 281. The bulb 283 of thermal switch 285 is secured at one of the upper precooler troughs 241 so that it is in contact with the liquid as it flows onto the belt. The switch 285 controls solenoid valve 279. Thus the amount of cooling is regulated by the temperature of the precooled liquid to be frozen.

GENERAL ARRANGEMENT As may be seen in FIGS. 1 and 3, the cold portions of the ice maker are enclosed in a cabinet 287 which is comprised of readily removable insulated panels joined at their edges by angle strips 289. Thus the front, rear, and sides of this cabinet may each be removed in one piece for ready service access. Since the slant portions of frame are cantilevered, replacement of belt 39 is simple after removal of the side and rear cabinet sections, the rundown pan 257, and the splash pa.n 262. Disconnecting rods 43 permits bearing blocks 31 to slide downward and to the left along with idler pulley 37 producing clearance for removal of belt 39. A thin section of the cabinet projects at the lower front center so that gear motor 291 may be mounted outside the insulated space. lts output shaft 61 projects through the panel with drive sprocket 59 on the inside. Thus the motor heat is excluded.

What is claimed is:

1. In a congealing apparatus having an endless metal belt including an outer surface upon which ice may be formed and a pair of refrigerated plates presenting grooved surfaces respectively continuous with the runs of said belt, each plate having its grooved surface in contact with the inner surface of the belt, apparatus for maintaining a flow of hydroscopic antifreeze heat transfer liquid lubricant solution comprising liquids of different volatilities in said grooves, said apparatus comprising, a reservoir containing a supply of said lubricant solution means for supplying said lubricant solution to said grooves, from said reservoir means for returning said lubricant solution to said reservoir after passage through said grooves wherein the solution becomes diluted and rectifying means in fluid intercommunication with said reservoir, said rectifying means including means for maintaining a predetermined temperature therein corresponding to the boiling point of the desired concentration of said diluted lubricant solution.

2. Apparatus as described in claim 1 wherein said means for maintaining a predetermined temperature includes an electric immersion heater and a thermal switch operatively connected to said heater.

3. Apparatus as described in claim 2 wherein said rectifier includes a reflux condenser.

4. Apparatus as in claim 1 wherein said reservoir is connected to said rectifier by a pair of convection flow tubes at different elevations, through which said lubricant solution flows whereby the solution concentration in said reservoir is maintained substantially the same as the solution concentration in said rectifier 

1. In a congealing apparatus having an endless metal belt including an outer surface upon which ice may be formed and a pair of refrigerated plates presenting grooved surfaces respectively continuous with the runs of said belt, each plate having its grooved surface in contact with the inner surface of the belt, apparatus for maintaining a flow of hydroscopic antifreeze heat transfer liquid lubricant solution comprising liquids of different volatilities in said grooves, said apparatus comprising, a reservoir containing a suppLy of said lubricant solutions, means for supplying said lubricant solution to said grooves, from said reservoir means for returning said lubricant solution to said reservoir after passage through said grooves wherein the solution becomes diluted, and rectifying means in fluid intercommunication with said reservoir, said rectifying means including means for maintaining a predetermined temperature therein corresponding to the boiling point of the desired concentration of said diluted lubricant solution.
 2. Apparatus as described in claim 1 wherein said means for maintaining a predetermined temperature includes an electric immersion heater and a thermal switch operatively connected to said heater.
 3. Apparatus as described in claim 2 wherein said rectifier includes a reflux condenser.
 4. Apparatus as in claim 1 wherein said reservoir is connected to said rectifier by a pair of convection flow tubes at different elevations, through which said lubricant solution flows whereby the solution concentration in said reservoir is maintained substantially the same as the solution concentration in said rectifier. 